Author

Date of Graduation

Document Type

Degree Name

Degree Level

Graduate

Department

Civil Engineering

Advisor

Michelle L. Bernhardt

Committee Member

Norman D. Dennis

Second Committee Member

Richard A. Coffman

Keywords

Analogue soil, Granular material, Triaxial

Abstract

The factors affecting the positive volumetric strain, or dilatancy, typically observed in response to shearing of a dense granular material have long been investigated; however, there still lacks a direct relationship between particle shapes and the resulting dilatant response. The typical Mohr-Coulomb strength parameter associated with granular material is known as the effective friction angle (φ’). For a dense granular assemblage, the peak friction angle has been described as being comprised of a dilatant friction angle (φ’d) component and a critical state friction angle (φ’cv) component. While the topic of dilatancy and factors (both inherent and extrinsic) affecting its behavior are understood by researchers, added complexity exists due to the dependency of the dilatation angle on features such as density, confining stress, and stress path.

With continuous innovation in additive manufacturing (AM), the technology has encompassed a broader spectrum of users including scientists and engineers. AM provides a new avenue for understanding the effect of particle shape on the dilatant response of granular material by providing the ability to change shape geometry while maintaining consistent material properties. It is hypothesized that an AM-fabricated analogue soil sample can then be used in a laboratory setting. A preliminary investigation was carried out to identify the various AM technologies available and their associated materials. After examining the strength and stiffness characteristics of the various materials, two separate AM technologies were selected. An analogue soil sample was fabricated using each device and was tested in consolidated drained triaxial compression. The analogue soils provided a shearing behavior similar to that of natural granular materials, thus indicating its feasibility for additional studies in geotechnical engineering.